Amplitude detecting device

Abstract

An amplitude detecting device of the present art increases the slope of the change in output voltage corresponding to the change in amplitude of an input signal to improve the detection accuracy of amplitude change of input signal, without changing the dynamic range of the device. An amplitude detecting device of the art includes a plurality of amplifiers that amplify an input signal according to a predefined amplification rate, an amplitude detector that detects the amplitude of the signal amplified by the amplifiers, an operation circuit that operates the signal detected by the amplitude detector and obtains the amplitude value of the input signal, and a switch circuit that sets whether the signal detected by the amplitude detector is to be transmitted to the operation circuit or not.

1. An amplitude detecting device comprising:
 a plurality of amplifiers for amplifying an input signal; 
 an amplitude detector for detecting an amplitude of a signal amplified by the amplifier and generating a current corresponding to the amplitude; 
 an operation circuit for adding each current generated by the amplitude detector and converting the added current to a voltage to obtain an amplitude value of the input signal; and 
 a switch circuit for setting whether a signal detected by the amplitude detector is transmitted to the operation circuit or not. 
 
     
     
       2. The amplitude detecting device according to  claim 1 ,
 wherein the plurality of amplifiers is connected in series. 
 
     
     
       3. The amplitude detecting device according to  claim 1 ,
 wherein the switch circuit sets whether signals detected by some consecutive amplitude detector are transmitted to the operation circuit or not. 
 
     
     
       4. The amplitude detecting device according to  claim 1 ,
 wherein each of the plurality of the amplifiers has an amplification rate being variable based on a control signal. 
 
     
     
       5. The amplitude detecting device according to  claim 1 ,
 wherein each of the plurality of amplitude detectors has a current amplification rate being variable based on a control signal. 
 
     
     
       6. The amplitude detecting device according to  claim 1 ,
 wherein the operation circuit includes a variable resistor for changing a value of a resistance by a control signal so as to convert the added current into the voltage. 
 
     
     
       7. The amplitude detecting device according to  claim 1 ,
 wherein the operation circuit converts the added current including the additional charge or discharge current into a voltage. 
 
     
     
       8. The amplitude detecting device according to  claim 1 ,
 wherein the input signal transmitted to each of the amplifier and the amplitude detector is transmitted through a coupling capacitor. 
 
     
     
       9. An amplitude detecting device comprising:
 a plurality of amplifiers for amplifying an input signal; 
 an amplitude detector for detecting an amplitude of a signal amplified by the amplifier; 
 an operation circuit for operating the signal detected by the amplitude detector and obtaining an amplitude value of the input signal; 
 a switch circuit for setting whether a signal detected by the amplitude detector is transmitted to the operation circuit or not; and 
 a control circuit for controlling the switch circuit, the control circuit including a comparator for comparing the signal operated by the operation circuit with two reference signals set beforehand, and controlling the signal operated by the operation circuit to take a position between the two reference signals. 
 
     
     
       10. The amplitude detecting device according to  claim 9 ,
 wherein the amplitude detector generates a current corresponding to the amplitude of the signal amplified by the amplifier, the operation circuit adds each current generated by an amplitude detector and converts the added current to a voltage. 
 
     
     
       11. The amplitude detecting device according to  claim 9 , further comprising:
 a comparator for comparing voltages of the signal operated by the operation circuit at a comparison time predefined.